6 - Coordination and Responding to Stimuli Flashcards Preview

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Flashcards in 6 - Coordination and Responding to Stimuli Deck (47)
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1

What is a stimulus?

Any change in the internal or external environment

2

What are receptors?

- Detect a stimulus
- Receptors in the sense organs are groups of cells that detect external stimuli
- e.g. Rod and cone cells in the eye detect changes in light

3

What are effectors?

- Cells that bring about a response to a stimuli
- Include muscle cells and cells found in glands (e.g. the pancreas)
- Effectors respond in different way (muscles contract whereas glands secrete hormones)

4

How do receptors and effectors communicate?

Via the nervous system, the hormonal system or both

5

What are sense organs?

The eyes, ears, nose, tongue and skin

6

What is the CNS?

- Central nervous system
- Made of neurons
- Consists of the brain and spinal chord only
- The job is to coordinate a response
- The high speed electrical impulses produce a rapid response
- When receptors detect and stimulus they send electrical impulses along sensory neurons to the CNS
- The CNS sends electrical impulses to an effector along a motor neuron

7

What are the neurons in the CNS?

Sensory, Relay, Motor

8

What are reflexes?

Automatic responses to certain stimuli which reduce changes of being injured
e.g. if a bright light is shone in the eye the pupil automatically get smaller to stop them being injured

9

Give an example of the reflex arc

- Cupcake candle burns finger
- Stimulation of pain in the receptors
- Impulses travel along the sensory neuron
- Impulses are passed along a relay neuron via a synapse
- Impulses travel along a motor neuron via a synapse
- When impulses reach muscles it contracts

10

What is the reflex arc?

Stimulus - Receptor - Sensory neuron - relay neuron - Motor Neuron - Effector - Response

11

What is the reflex arc?

Stimulus - Receptor - Sensory neuron - relay neuron - Motor Neuron - Effector - Response

12

What is the role of the cornea?

Refracts light into the eye
- Transparent with no blood vessels to supply it with oxygen so oxygen diffuses in from the outer surface

13

What is the role of the conjunctiva?

Lubricates and protects the surface of the eye

14

What is the role of the iris?

Controls the diameter of the pupil allowing how much light is let in

15

What is the role of the lens?

Focuses light on the retina (the light-sensitive part covered in light receptors called rods and cones)

16

Rods and Cones

Rods - more sensitive in dim light but can't sense colour
Cones - sensitive to colours but aren't so good in dim light. Found all over the retina but are loads at the fovea

17

What is the role of the optic nerve?

Carries impulses from the receptors to the brain

18

How does the eye adjust to bright light?

- Bright light triggers a reflex that makes the pupil smaller, allowing less light in
- Light receptors detect light and send a message along sensory neurons to the brain. The message travels along a relay neuron to a motor neuron which tells circular muscles to contract
- The opposite happens in dark light

19

How does the eye look at distant objects?

- Ciliary muscles relax
- Suspensory ligaments pull tight
- This makes the lens go thin (less curved)

20

How does the eye look at near objects?

- Ciliary muscles contract
- Slackens the suspensory ligaments
- The lens becomes fat (more curved)

21

Long-sighted people

- Unable to focus on near objects
- The cornea or lens doesn't bend the light enough or the eyeball is too short
- The images of near objects are brought into focus behind the retina

22

Short-sighted people

- Unable to focus on distant objects
- The cornea or lens bends the light too much or the eyeball is too long
- The images of distant objects are brought into focus in front of the retina

23

Short-sighted people

- Unable to focus on distant objects
- The cornea or lens bends the light too much or the eyeball is too long
- The images of distant objects are brought into focus in front of the retina

24

What are hormones?

Chemicals released directly into the blood
- Carried in the blood plasma to other parts of the body but only affect particular cells (called target cells) in particular places
- Control things in organs and cells that need constant adjustment
- Produced in various glands
- Travel slowly and last for a long time

25

ADH

Source - Pituitary gland (brain)
Role - Controls water content
Effect - Increases water permeability of the kidney tubules to water

26

Adrenaline

Source - Adrenal glands (on top of kidney)
Role - Readies the body for a 'fight or flight' response
Effect - Increases heart rate, blood flow to muscles and blood sugar levels

27

Insulin

Source - Pancreas
Role - Helps control blood sugar lever
Effect - Stimulates the liver to turn glucose into glycogen for storage

28

Testosterone

Source - Testes
Role - Male sex hormone
Effect - promotes male secondary characteristics (e.g. facial hair)

29

Progesterone

Source - Ovary
Role - Supports pregnancy
Effect - Maintains the lining of the uterus

30

Oestrogen

Source - Ovaries
Role - Female sex hormone
Effect - Controls the menstrual cycle and promotes female secondary characteristics (e.g. widening of hips)